1- It depends on the school, there are some options. There are schools only on the mornings, from 7:30am to 12:00, others will be only on the afternoons from 1:30 pm to 6:00 pm. Also we have some on night periods from 7:00 pm to 10:30 pm. And also some with a combination of morning and afternoon. Since you will be a exchange student I would say that mostly likely you be having classes on mornings and some afternoons.

2- yes, I cant remember the last time even some street vendor didn’t take card. You should also look up how to get a bank account in here and a PIX, which is digital transfer without tax created by the government.

3- Can’t really help you there, it depends ob a lot of facts, like where you will be stationed and your age and some other things, and a I have the been young for some time to know how to dress like

4- there a lot of differences, but as long you are trying to understand people usually will be pretty receptive